RFR: 8338662: Shenandoah: Remove excessive ShenandoahVerifier::verify_during_evacuation

[Y. Srinivas Ramakrishna]

On Tue, 20 Aug 2024 10:22:23 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> `ShenandoahVerifier::verify_during_evacuation` is a relaxed version of `ShenandoahVerifier::verify_before_evacuation`. In current code, "during" verification is called shortly after "before" check, which really gains us nothing checking-wise, and only really wastes verification time. This is the only "during" verification check we have, all other checks verify things before/after the phases. It makes sense to remove "during evac" verification check for extra debug performance and cleanliness. 
> 
> Additional testing:
>  - [x] Linux x86_64 server fastdebug, `hotspot_gc_shenandoah`
>  - [ ] Linux x86_64 server fastdebug, `all` with `-XX:+UseShenandoahGC -XX:+ShenandoahVerify`

LGTM.

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Marked as reviewed by ysr (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/20641#pullrequestreview-2251773370